Rust, Danged Rust

P. McKinley

P. McKinley

Joined
Jan 27, 2008
Messages
2,010
The other day I finished up a knife that I spent quite a few hours on and am(read: was) quite proud of. This morning the check arrived from the client and I had been ready to package and ship it out tomorrow. So, in preparation I was about to give the piece a final going over when something caught my eye. I noticed spots... little teenie, near microscopic spots all over the blade but, only on one side. Under magnification I quickly determined that I was looking at rust. I was near tears and almost sick to my stomach. This piece was ordered by the customer as a gift to her husband for their 25th wedding anniversary on Oct 1st. I worked damn hard on this knife, there's no way I can send this off in this condition, and now I'm just numb.

The answers to your immediate questions:
-The blade is Aldo's 52100.
-Normalized three times at descending temps 1600, 1500, 1400 degrees.
-Heat treat regime:1475 soak for 12 min, full quench in new canola, temper at 420 for 2 hours x 2.
-Finish ground after heat treat, hand sanded to 1200 with 3M Wet/Dry.
-Cleaned w/ acetone, lightly coated with WD40 wrapped in paper towel and tape to complete the build
-Sheath is unlined veg tanned leather that was cased, dyed, and wet-formed(all in one step) then dried for two days before finishing.

Photos:
This is NOT dust or lint you are looking at.










Here's the knife:


I posted a thread on the knife here:http://www.bladeforums.com/forums/showthread.php/991904-Fancy(for-me)-Drop-Point-Hunter

So - How'd this happen? How do I fix it? How do I avoid it in the future?

Any thoughts would be greatly appreciated.

Thanks,

Peter
 
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In my experience, WD40 does not leave much behind to prevent rust once it evaporates, and it evaporates fast. I have had better luck with Renaissance Wax, LPS 3, Marine Tuf-Cloth, and mineral oil. Obviously not all of these treatments are appropriate for a fine knife like that, but a coat of wax on the blade might have prevented the rust. Also, where was the knife stored? How's the ambient temperature and humidity? Rust on one side only suggests condensation, or perhaps some sort of spatter/contamination.
 
Paper towel is not much good .You should use VPI paper [vapor phase inhibiter] and RIG preservative grease .I've used those two for years !

I'm curious to know why it's only on one side ?? Bolster material ? In the second photo ,do I see the same problem on the bolster ? Could the sheath be contaminated ? Did you pick up steel filings on one side of the knife in the fitting process ?? Wet those filings would rust then in turn rust the blade .
 
Not 2 days ago a knifemaker friend told me he has had problems in the past with WD40 coated blades and dust. According to him, dust particles penetrate the WD40 and act as moisture conduits. Please note that this is only hearsay, but maybe there's some validity to it. Perhaps this blade got a light coating of dust on the side facing up before you were able to apply the towel....?

Cheers ROdy
 
Carbon steel can be very disapointing at times. A lot of makers use it and I do in Damascus. Otherwise I use what is concidered a good stainless. Give Elmax a try or M390. Yes there are others. Just a few knives made with this stuff will probably get you to change from carbon steel. They are easy to grind in either a soft or hardened state,. provide excellent edge holding and are easy to sharpen. No, they don't rust.Frank
 
Ohh man, thats just breking my heart to see this on such a beautiful, well made knife. I dont really have a solution for you but I would have tried to rub it gently in a lengtwise motion with fine steel wool and oil. The pros here might chime in with better solutions.
When I wetform my sheaths, I´ll coat the blade with a thin layer of leathergrease to prevent rust. I´m sure there are better products out there, but thats just my "grab what you have" solution.

Hope you work it out.

Brian
 
Several months ago I had 4 blades of 1095 ground and buffed to a satin finish. The next morning I noticed tiny spots of rust very similar to what you experienced on your blade and they were only on one side. I couldn't figure out what was going on, but then I remembered one of my friends had been in the shop the day before and was having a very rough allergy day. He had sneezed repeatedly in the vicinity of the 1095 blades and I deduced that it was the aerosol saliva that had caused the tiny rust spots.
 
Thanks for the input folks.

Mete - The bolsters are hardened O1 steel with mild steel pins. I actually don't see the same issue with the bolsters. The spots you may be seeing are likely dust, as I didn't wipe them off well prior to these photos. Sheath contamination could be the culprit, yes. Steel filing contamination may be the cause, although I think rather unlikely as I'm pretty anal about cleaning and protecting the polished blade during the various phases of the build..... possible, but its a stretch for me.

Here's a thought..... decarb.
I was speaking to a rather accomplished blade smith(his business rhymes "builder fools" :p) on the phone last night and he brought this up as a possibility. Although the blade was finish-ground after heat treat then hand sanded from 400 to 1200, it might be possible that I did not remove the entire layer of decarb. To me, this explanation makes sense.

or

Did I screw up the heat treat in such a manner where this could have occurred. I use a propane forge w/ muffle tube for my heat treat. I'm pretty confident that I achieve and maintain proper temps and times, but with a gasser and my modest degree of competence... its possible.

Thanks all. I appreciate you help.

Peter
 
CM Forge said:
Several months ago I had 4 blades of 1095 ground and buffed to a satin finish. The next morning I noticed tiny spots of rust very similar to what you experienced on your blade and they were only on one side. I couldn't figure out what was going on, but then I remembered one of my friends had been in the shop the day before and was having a very rough allergy day. He had sneezed repeatedly in the vicinity of the 1095 blades and I deduced that it was the aerosol saliva that had caused the tiny rust spots.
Click to expand...

Hmmmmmm, interesting. My daughter has a cold and was in the room when the good photos were taken the other day.

oh, and GO AGGIES!!
 
I see spots on the handle, bolster, and blade in the photos. They seem white more than dark. This looks like some sort of dried chemical or compound. Try cleaning with a soft cloth and Flitz, followed by a good cleaning and oiling with something like ballistol.

I don't know what the exact cause of yours is , but I call this phenomena "Bloom". It appears to be the drying and crystallization of chemicals on the surface. It seems to happen on one side worse than the other, so I usually suspect that it was caused by something misting in the air. One could open a soda/beer can across the room, and the fine mist of particles can drift on the air currents. The same phenomena can happen with a sneeze, cough, or even talking/singing. Minute drops of moisture are expelled on the breath and settles on surfaces within the area. The droplets can dry up and leave their solutes, or start tiny rust spots.
I have to wipe down every blade after a show or display or I can usually guarantee spots will appear due to this.

In a non-temperature controlled room ( shop or garage exposed to cooling and warming daily), as the air temperature falls, microscopic drops of water can condense on dust/grit particles which have settled on the upper blade surface, dissolve chemicals in that dust, and then evaporate as the air temp rises. This leaves behind micro dots of rust/corrosion/bloom.

If cleaning and oiling do not remove the spots, often a quick re-sanding with your final grit will remove them. Use a good penetrating oil as the lubricant.

Another possible cause could be that the wet forming of the sheath left moisture in the micro-pores of the steel, and it eventually repelled the oil away from those tiny spots and caused the corrosion or bloom to form when the air hit the spots. That would not explain why it seems identical on the bolster and even handle, though.

BTW, was it in the sheath after finishing and before the spots appeared? I get similar spots from leaving a knife in the sheath for even a few days sometimes.
 
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What about the choji oil ? For me, it's the perfect oil protector for all blades.
 
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Choji oil (clove oil extract and mineral oil) is a good blade treatment, but it is just one of many good oils. Just because the Japanese use it almost exclusively does not make it superior.

I find WD-40 about the worst blade protectant oil there is. Great for cleaning and such, but not as a final protectant.
 
Bigblue17 said:
I was speaking to a rather accomplished blade smith(his business rhymes "builder fools" :p) on the phone last night and he brought this up as a possibility. Although the blade was finish-ground after heat treat then hand sanded from 400 to 1200, it might be possible that I did not remove the entire layer of decarb. To me, this explanation makes sense.
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Builderfool here,
I had a problem with a batch of seven knives about a year ago. A dealer called me and said that the knives he had received from me were rusting. I had them shipped back and called another dealer with knives from the same batch... sure enough, rust.:( I got them home cleaned them up set them aside and waited. Two of them rusted in the same pattern as before. I sanded the hell out of them and it went away. I know that when I first made these ones, there was a layer of decarb that had to be sanded off in order for a homogenous finish. The pattern of rust was the same pattern I was seeing in the decarb(that orange peel look), previously.

So my question to Mete and Stacy (and whoever else) is am I wrong to believe that residual decarb is more prone to rust? As the carbon gets cooked out, I can only imagine that alloys like Cr, Mg, Mb are suffering the same fate. In a steel like 52100, what little rust inhibiting additives it has must be absent in the decarb layer.

Another problem I had(which doesn't relate to Peter's problem) was with my etch. I use a mixture of selenium dioxide and chlorine to create a hydrochloric acid of sorts. I usually neutralize it with water and baking soda. But used Windex after reading that it works for ferric chloride. Well I am no chemist but the ammonia in the windex mixed with the acid I had previously made, created a fast acting oxidizer that made a home in all the nooks and crannies of the etch I was so proud of. It was all well and good while oiled... but as soon as the blade was wiped clean and dried, the reaction started up again. The rust grew like a chia pet. Horrible.

Back to Peter's dilema...

I think it is still possible to sand out those marks if you are careful.
 
Decarb - the reason that carbon is lost is that it's an atom much smaller than the other elements in steel so that the diffusion to the surface is faster and it combines with oxygen easily.
The area around the carbides may be lower carbon still and more prone to rust. I'd try to polish it out.

Rick what kind of steel do you use with Mg and Mb ?? Some kind of secret Aldo steel ?? LOL
 
I cannot answer the problem directly, but I do have some general thoughts...

There's no such thing as "perfect". Having said that, I truly admire the craftsmanship displayed in that piece. That's a gorgeous, well-designed and beautifully-executed knife!

WD-40 is not used in my shop or home. At all. This may start a firestorm, but my very strong opinion is that it's mostly hype, and there are much better alternatives for every job it's supposed to do so well. When I want to protect blades during storage or while working on their handles, I use mineral oil or layout dye before wrapping them with adhesive tape.

All steel rusts, eventually. There's just no getting around that unless you only make knives that are coated in wax and kept in a climate-controlled case, and never used or touched or breathed on or looked-at funny.

Surface finish is a really big deal when it comes to corrosion-resistance, regardless of alloy. The smoother the surface, the less chance for moisture and gunk to adhere to it and react chemically.

If you cannot stand small pits, patina, staining etc, 52100 is a very poor choice. Even CPM-154 at 58Rc with a 2000-grit finish can develop tiny pitting under normal use! In my experience, those minor flaws do not demonstrably harm the function of the knife, except on the very edge, which is easily cleaned up.

But here's the rub: I think Stacy is really onto something when he speaks of chemical contamination. I've never seen white rust, so it may well be scale or oxides on the surface, not rusting iron.

If it were my knife, I would clean it gently but thoroughly and send it on. It's well-ground from excellent steel, and will outlast us all with a bit of care.
 
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james terrio said:
All steel rusts, eventually. There's just no getting around that unless you only make knives that are coated in wax and kept in a climate-controlled case, and never used or touched or breathed on or looked-at funny.
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This brings to mind the quantum physics discussions often labeled as "Schrödinger's cat". Put a perfectly rust-free knife in a perfectly sealed container (presumably along with a packet of something that absorbs any trace of watcer molecules in the container). Set the container aside for some predetermined period of time. Will the knife rust? Without opening the container you could make assumptions and assertions about rust, but they could not be confirmed. Opening the container to observe the knife ends and invalidates the test by introducing new elements.

Your point that there are no perfect knives is absolutely true. That, however, is cold comfort to one who is about to send a knife to someone who wishes to give a "perfect" knife as a gift for a very special occasion.

As has been noted previously in this topic, WD40 is not what most people think it is, and it does not do what most people think it does. It does not prevent rust. Wax does a better (if still imperfect) job of that.

I second the recommendation of Renaissance Wax. It's expensive, and I'm not sure it's really any better than the less expensive waxes, but you don't need much to coat a blade, and it does give one peace of mind.

- Greg
 
WD-40 is good for loosening rust-encrusted bolts, nuts and screws...and starting fires, but no good for coating blades. The layer it provides is to thin, to fluid and evaporates quickly leaving behind a film that acts as a dust, and condensation magnet. I have had semi-stainless blades (3V for example) rust inside of dry kydex sheaths, after using WD-40 to coat the blade. Since I make mostly hard-field use knives I have used straight motor-oil, bar/chain oil, and gun grease to great effect, have had rust problems since.

On your knife I would probably try Flitz w/ a scotchbrite pad first, then re-buff.
 
mete said:
Rick what kind of steel do you use with Mg and Mb ?? Some kind of secret Aldo steel ?? LOL
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Ha!... I was just quickly typing elements for example. Mg should have been Mn and Mb should read Mo... lol. Watch out, Mete... I'm gunnin' for your job! I like my versions better:p
 
I just wanted to add that I'm not a big fan of windex to neutralize in, every time I use it I come back to find further oxidation on whatever I etched with ferric. Probably it's just my technique, but I usually just use high alkaline solution of sodium bicaonate or carbonate(baking soda) and a little dish or castile soap in water, same as my slack tubs and grinder buckets, and with that have never had a prob.

Personally, I don't get the appeal of windex as a neutralizer.
 
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